ticking sound is now knocking sound & dead miss

[gejandsons]

2004 merc OB 50 HP - Had ticking noise from engine for last 10 tanks of fuel - Last trip out, lost power & ticking turned into a knocking sound. Immediately shut off engine & trolled in. removal of plugs found gap closed completely on middle cylinder.
Connecting rod failure?

 

[CLAYC]

Re: ticking sound is now knocking sound & dead miss

Metal on top of piston will cause gap closure.. I bet something broke inside of cylinder: piston or sucked a reed.

 

[rboating]

Re: ticking sound is now knocking sound & dead miss

well the only way i can see something closing the gap on the plug if if you dropped something from the head or down the carb..a nut possibly? must have came loose or busted and dropped on top of the piston.the piston will only go up so far even in the event of a connecting rod failure. and more than likely the ridge from the piston will stop it from going to far.has to be something on top of it to press on the plug.might pull your valve covers and inspect the valves on that cylinder. might have lost a guide down there..they wear out... and thatll make the ticking sound as they are going...just some thoughts form the auto world there...